Whenever extraneous fluids are introduced into the body's cavities or passages, it is necessary that these fluids be drained before they accumulate. For example, following a surgical incision through the rib case in order to perform surgery on the lung, or following stab or bullet wounds which pierce the rib cage, fluids such as water, blood, or air may be deposited in the pleural cavity. If such fluids are allowed to accumulate in the pleural cavity, breathing becomes difficult and ultimately impossible. Therefore it is imperative that any fluids which are deposited in this cavity be removed quickly.
In order to withdraw fluids from the body, a tube is usually connected at one end to the cavity to be drained and at the other end to a source of vacuum or suction. Usually the tube is first connected to a chamber which is maintained at a vacuum so that the fluid is collected in the chamber.
While a stationary source of vacuum may be readily available in a hospital, there are many times when a movable source is needed, for example, at the site of an accident or wounding and while the patient is being transported to a hospital. In addition, a portable source of vacuum may be used in a hospital after surgery when a patient is being moved to the recovery room. In some cases, it may even be desireable to provide an ambulatory patient with such a device to enable him to carry it with him wherever he goes.